Ideas

Customize the default WP.org download package

When you're downloading the WP.org package, there should be options for default themes and widgets to include.

These optional themes and widgets should be the ones included in every WP.com account.

That would make it a snap to move from a WP.com to WP.org account. You could simply select the elements you were using, and they would be automatically included in your freshly installed WP.org package!